In consideration of the fact that there is an ongoing increase in (bio-)chemical and genetic analyses and assays, a strong demand for the automated pipetting of fluids can be observed.
In recent years, many efforts have been made to develop new automated pipetting devices most often provided with a plurality of pipettes enabling plural pipetting operations in parallel. Each of the pipettes is provided with a pipetting tip connected to a pump by means of a pump conduit to transfer pump-generated negative or positive pressure to the pipetting tip for aspirating and dispensing of fluids, respectively. Conventionally, plunger pumps are being used for pipetting operations which advantageously allow for high-precision pipetting of fluids, however, typically are heavy in weight and thus may not be moved together with the pipetting tips due to an undesired strong increase in inertia. This especially applies to the case of independently operable pipettes requiring each pipette to be provided with a separate plunger pump.
Hence, plunger pumps are kept stationary when moving the pipetting tips and, for instance, are fixed to a base-plate, which, however, enlarges the overall dimensions of the automated pipetting device and hinders an integrated and compact design of the pipettes. Moreover, lengthy pump conduits in-between pump and pipetting tips aggravate various maintenance tasks (e.g. leakage detection) and disadvantageously enlarge dead volumes which, however, essentially influence precision of pipetting operations.
US-patent application No. 2008/0019878 A1 to Trump discloses a positioning device for pipettes in which a profiled rail accommodates a pump drive. While such positioning device makes the pump drive an integrated part of the profiled rail, such construction, however, disadvantageously requires the positioning device to be newly adjusted each time the pump drive has to be serviced. For that reason, maintenance of the pump drive due to failures will result in undesirably high costs. Furthermore, irrespective of the fact that plural pipettes require a rather complex construction, the positioning device may not be readily adapted to varying demands.